Development And Mechanic Analysis Of Limited Reamed Dynamic Compress Intramedullary Nail

Objective: To develop a new kind of intramedullary nail. Its foundation of femoral anatomy was studied and its mechanics of materials and biomechanics were experimented in an effort to provide theoretical evidence for advanced reseach and clinical application.Methods: 1) After removing adherent soft tissue , 8 cadaver femur undergone antiseptic treatment with formalin were used for observing the general anatomy and shape of the medullary canal. The measurement of (1) intramedullary nail-related anatomic parameters, (2) numerical values of diameter of the coronal plane and sagittal plane of the femur medullary canal, (3)numerical values of diameter of the coronal plane and sagittal plane of stricture region of the femur medullary canal,(4) thickness of the cortex of the femur. 2)The mechanic characteristics testing of LRDCIN: (Daxial load testing, (2)axial tension testing, (3)three-point bending testing, (4)torsion testing.Results: The femur medullary canal ranges from the basal part of lesser trochanter to 8cm above the distal articular facet. The cortical bone is thick in the mid-shaft while thin in the amphi-diaphysis. Radian radius of the non-cancellous bone region is 115.01 28.10cm. The most stricture section is at 2cm above the midpoint between greater trochanter and lateral epicondyle, with the sagittal plane diameter being 10.56 1.49mm, and the coronal planediameter 10.08 1.67nnn. 2) LRDCIN was designed to have bilateral wings and no slot. Therefore it has high stiffhess.(l) The Pcr of 9.0mm LRDCIN with 1.0mm bilateral wings is 3153 127N. Its strength is far bigger than required physiologically. (2)The bending stiffness of LRDCIN is higher than GK nailing.The stress of 9.0mm LRDCIN with 1.0mm bilateral wings is 612 59 , and its deflection is 0.22 0.02mm, which is about 1.4 and 1.5 times than GK nailing. (3) The GJ and torsinal degree of LRDCIN with 1.0mm bilateral wings is 2.6 and 1.5 times than GK nailing with the same diameter.The data were dealt with student-t test and the difference is signifcant.Conclusions: LRDCIN is a new kind of intramedullary nail with good mechanic characteristics. It is a new choice for internal fixation and will have good application perspectives.